What screening is recommended for an elderly male with a family history of intracranial aneurysm (ICA) behind the right eye causing diplopia (double vision)?

Screening for Intracranial Aneurysms in Elderly Males with Family History

Yes, screening with MRA or CTA is recommended for an elderly male with a family history of intracranial aneurysm, particularly if there are two or more affected first-degree relatives. 1, 2

Risk Stratification Based on Family History

The strength of your screening recommendation depends on the number of affected relatives:

• Two or more first-degree relatives with aneurysm or SAH: Screening is strongly recommended (Class I; Level of Evidence B), as this defines familial intracranial aneurysm syndrome with approximately 8% risk of harboring an unruptured aneurysm 1, 2

• One first-degree relative with aneurysm: Screening should be offered, especially with additional risk factors (hypertension, smoking, female sex), as the relative risk is 4.2 compared to the general population 1, 2

• General population without family history: Screening is not recommended, as it is not cost-effective and may cause more harm than benefit 1

Additional Risk Factors That Strengthen Screening Indication

Beyond family history, these factors increase the likelihood of detecting an aneurysm and should prompt screening even with only one affected relative 2, 3:

• Current or former cigarette smoking
• History of hypertension
• Female sex
• Higher lipid levels
• Elevated fasting glucose

Recommended Imaging Modality

MRA without contrast is the preferred initial screening method 1, 2, 3:

• Sensitivity: 69-93% for aneurysms >3-5 mm 1, 2
• Specificity: 89% 3
• Non-invasive with no radiation exposure, making it ideal for screening 2, 3

CT angiography is an acceptable alternative 1, 2:

• Sensitivity: 77-97% for aneurysms as small as 2-3 mm 1, 2
• Involves radiation exposure, less ideal for repeated screening 3

Catheter angiography remains the gold standard but should be reserved for symptomatic patients or when MRA/CTA findings are equivocal, given its invasive nature and <0.5% permanent neurological morbidity risk 1, 4

Screening Frequency and Duration

Screen every 5-7 years from age 20 to 80 years if two or more first-degree relatives are affected 3, 5:

• Long-term data shows aneurysms detected in 11% at first screening, 8% at second screening, 5% at third screening, and 5% at fourth screening 5
• The yield remains substantial even after two negative screens, with 3% developing de-novo aneurysms 5
• One patient developed a ruptured aneurysm 3 years after a negative screen, suggesting intervals may need to be shorter in some cases 5, 6

For elderly males specifically: Continue screening until age 65-80 years, as life expectancy and competing health risks must be considered 3

Critical Risk Factor Modification

Regardless of screening results, aggressively address modifiable risk factors 2, 3:

• Smoking cessation is critical: Smoking is one of the strongest modifiable risk factors for both aneurysm formation and rupture 2, 3
• Blood pressure control: Reducing diastolic blood pressure by 6 mmHg produces a 42% reduction in stroke incidence 3
• Avoid sympathomimetic drugs: Including cocaine and phenylpropanolamine 3
• Limit alcohol consumption: Heavy use is an independent risk factor for SAH 3

Important Caveats

The family member's aneurysm causing diplopia suggests a symptomatic lesion, which is clinically significant 4:

• Symptomatic aneurysms causing mass effect (like cranial nerve palsies with diplopia) warrant urgent neurosurgical evaluation and strong consideration for treatment regardless of size 4
• This distinguishes it from asymptomatic screening scenarios and suggests higher risk 4

Screening is not without risks 7:

• One older study suggested screening 1000 individuals three times resulted in poor outcomes in 14 patients (from screening/treatment complications) versus 15 without screening, questioning cost-effectiveness 7
• However, this 1999 study used older imaging and surgical techniques; modern data from 2014 shows substantial yield with serial screening 5

If an aneurysm is detected, treatment decisions must consider 1, 4:

• Patient age and life expectancy
• Aneurysm size (rupture risk increases significantly with size >7mm) 1
• Location (posterior circulation and posterior communicating artery have higher rupture risk) 1
• Morphology (irregular shape, daughter sacs increase rupture risk) 4
• Symptomatic versus asymptomatic presentation 4

Special genetic conditions warrant screening even without family history 2, 3:

• Autosomal dominant polycystic kidney disease (10-11.5% prevalence of aneurysms) 3
• Type IV Ehlers-Danlos syndrome 3
• Coarctation of the aorta 1, 3
• Microcephalic osteodysplastic primordial dwarfism 1